Universal protractor



March 27, 1934. F. c. WEBBER UNIVERSAL PROTRACTOR Filed April 24 1930 ATTORNEY Patented Mar. 27, 1934 UNITED STATES PATENT OFFICE 1 Claim.

The head forms the body element and is primarily and preferably made of transparent material. An arm is hingedly secured to the graduated body element having a marked center line and having at least one of its edges graduated for'measurement purposes. The base of the body element is parallelly disposed to that of the base line passing through the center. Graduations are disposed upon the base for measurement purposes. The arm is hingedly secured to the body element having an adjustable center with means for tightening the arm relative to the body element.

The primary purpose of my invention is to enable the user thereof to read in degrees and pitch lines simultaneously.

A further object of my invention consists in providing a device for use by draftsmen, artisans, mechanics and others to enable them to simultaneously locate the arm either in degrees or in pitch lines and to indicate measurements along the base of the body element and along an adjustable arm hingedly disposed upon the body element at one and the same time.

A further object of my invention consists in providing an instrument, the inner surface of which, lies in a common plane.

A still further object of my invention consists in providing a body element having a hinged arm secured thereto made in a manner to insure longevity.

With these and incidental objects in view, the invention consists in certain novel features of construction and combination of parts, the essential elements of which are set forth in the appended claim, and a preferred form of embodiment of which is hereinafter shown with reference to the drawing which accompanies and forms a part of this specification.

In the drawing: a

Fig. 1 is a plan view of my new and improved universal protractor.

Fig. 2 is a longitudinal, sectional, side elevation of the assembled device.

- Fig. 3 is a plan view of one of my new and improved devices illustrating the same in position for reading the pitch cut, or for making a pitch mark, of 45 degrees and indicating at the same time a 12-12 pitch.

Fig. 4 is a diagrammatical layout of pitch and degree lines illustrating in dotted position the readings that may be made simultaneously in degrees and pitch lines.

Like reference characters refer to like parts throughout the several views.

I preferably form my device of a transparent body element 1. Graduations 2 are disposed about the outer periphery of the body element which may be graduated into pitch line graduations. One or more additional graduated halfcircles 3 are disposed upon the face of the body element, the same being marked in degree grad uations. A base line 4 passes through the center 5 of the half-circle comprising the primary portion of the body element. A graduated base 5A is disposed parallelly to the base line 4 and graduations 6 are disposed along the base of the body element. A transparent arm 7 is hingedly secured to the body element with a center line 8 marked upon the arm. The center line 8 passes longitudinally of the graduated arm and passes through its center of rotation and also through the center of the base line of the body element.

A metallic hub 9 is disposed within the body eles5 ment and a metallic hub 10 is disposed through the base and forms the center of rotation of the graduated arm 8. An adjustable screw 11 passes through the respective hubs and an adjustable thumb screw 12 is threadably positioned upon the adjusting screw, the purpose of which is to develop and maintain a frictional engagement between the respective hubs that are fixedly positioned within the body element and within the arm. A dove-tailed connection is formed between the outer periphery of the body element and the graduated arm to form a suitable working connection between the body element and the graduated arm. An offset is formed within the arm to place the surface 13 of one side of the 10 body element and the surface 14 of the graduated arm in surface alignment with each other. The center line 8 passing longitudinally of the graduated arm is the line upon which the instrument should be read and the same passes simultaneous- 5 ly across the graduations forming the pitch line and the graduations showing degrees to permit the user of the instrument to read the graduations simultaneously. A line 15 is struck at right angles to the base to divide the semi-circular body element into two equal quarter circle divisions.

While the form of mechanism herein shown and described is admirably adapted to fulfill the objects primarily stated, it is to be understood that it is not intended to confine the invention to the one form of embodiment herein shown and described, as it is susceptible of embodiment in various forms, all coming within the scope of the claim which follows.

What I claim is:

A device of the class described, comprising a transparent body element with one semi-circular boundary having degree graduations thereon extending over 180 degrees, and having its circular edge formed at an obtuse angle to its graduated face, said body element having upon its degreegraduated face graduations representing pitch, a shouldered aperture formed through the transparent body element at the geometrical center. of the graduations, a shouldered bushing of a with a knurled nut, said arm being formed with an offset and angularly undercut portion in wiping engagement with the said angular edge of the body element to maintain the arm in contact therewith.

" FRANK C. WEBBER. 

